I would run away from your current bike mechanic.

I use a compound when I build wheels to do two things.

1.) Prevent oxidation and binding

2.) Keep a medium grip between nipple thread and spoke thread, preventing the spoke from working itself loose and needing to re-true the wheel.

Below is an example of a workable product, on the back wheel i use two different colors, so I don't have to bother mixing short and long spokes.

Lubrication with DW40 and Tri-Flow will remove friction between nipple and spoke. Riding rough asphalt you will be back to the bike-shop soon with loose spokes.